Waldron, Martin Augustine. "Virtue." The Catholic Encyclopedia. Vol. 15. New York: Robert Appleton Company, 1912. 3 Aug. 2020 .

This article was transcribed for New Advent by Barbara J. Barrett.

Ecclesiastical approbation. Nihil Obstat. October 1, 1912. Remy Lafort, S.T.D., Censor. Imprimatur. +John Cardinal Farley, Archbishop of New York.